The PC Trace module provides input
conditioning options for signals that are used to qualify operation in Start-Stop or
Windowed modes. For each of these (START, STOP, WINDOWED), there is a two-stage
synchronizer for asynchronous input signals, and an inverter. The PC Trace input
conditioning options are controllable using the PCTRACE_QUAL1 register with the
following bits:
- WINDOWED_INP_INV: This bit
inverts the input signal for Windowed trace mode selected in WINDOWED_INP_SEL.
When set to 1, the trace operation starts on the falling edge of the input, and
stops the rising edge of the input. When this bit is set to 0, the trace
operation starts on the rising edge of the input, and stops on the falling edge
of the input.
- WINDOWED_INP_SYNCH: This bit
passes the input signal selected in WINDOWED_INP_SEL through a two-stage
synchronizer.
- START_INP_INV: This bit inverts
the input signal for trace START operation selected in
PCTRACE_QUAL2.START_INP_SEL. When set to 1, the trace operation starts on the
falling edge of the input. When this bit is set to 0, the trace operation starts
on the rising edge of the input.
- START_INP_SYNCH: This bit passes
the input signal selected in PCTRACE_QUAL2.START_INP_SEL through a two-stage
synchronizer.
- STOP_INP_INV: This bit inverts
the input signal for trace STOP operation selected in
PCTRACE_QUAL2.STOP_INP_SEL. When set to 1, the trace operation stops on the
falling edge of the input. When this bit is set to 0, the trace operation stops
on the rising edge of the input.
- STOP_INP_SYNCH: This bit passes
the input signal selected in PCTRACE_QUAL2.STOP_INP_SEL through a two-stage
synchronizer.
Figure 13-7 describes the signal conditioning circuit available for each input qualifier
signal.